1. Field of the Invention
This invention relates to a device that is placed on an oar stop to dampen the sound produced by the rubbing of the oar stop against the oar lock as the oar is operated to propel and steer a boat.
2. Description of the Related Art
The problem of friction between an oar lock, which acts as the fulcrum or bearing surface when an oar is used to propel a boat, and the oar stop, which prevents an oar from sliding through the oar lock into the water if the oar is released by the rower when the oar is in its operating position, has been explicitly considered in two inventions--U.S. Pat. No. 709,667 and U.S. Pat. No. 1,389,988.
In U.S. Pat. No. 709,667 of Henry Ditchburn the invention consisted of a flanged metallic collar which pivotally separated into two halves to facilitate placement on the oar. After being properly oriented on the oar, these two halves were screwed together. To minimize noise by preventing the metallic collar from contacting the oar lock, Mr. Ditchburn's oar stop also included two or more thicknesses of leather. The leather collar thus formed was essentially a disk whose thickness exceeded the length of the portion of the metallic collar that paralleled and was adjacent to the shaft of the oar. The center of the disk had an aperture of the size that would precisely accommodate the shaft of the oar, and the outer radial dimension of the leather collar caused it to extend approximately the same distance from the shaft as did the flange on the metallic collar that was perpendicular to the shaft. To permit the leather collar to be placed on the oar and metallic collar, the leather collar had on one side a physical division running from the aperture to the outer radial perimeter of the leather collar and extending the full thickness of the leather collar. Radial screws secured the leather collar and the metallic collar by passing through the leather collar and the portion of the metallic collar that paralleled and was adjacent to the shaft of the oar. The tips of these screws were imbedded in either the shaft of the oar or a leather shield surrounding such shaft.
Although the leather would reduce the noise as compared to that resulting from the contact of two metallic surfaces, anyone who has ever climbed into a saddle knows that leather is far from a silent material. Moreover, leather absorbs water and is unlikely to float--a factor that would be of greater significant were the leather collar more readily replaceable.
William A. Rose, in U.S. Pat. No. 1,389,988, claimed an oar stop whose primary structural element was a series of leather strips laid around the shaft of the oar on top of each other, the length of each strip being such that the ends of each strip would just abut each other. These strips were secured to the oar by tacking their ends and by a metallic clamp. The metallic clamp was a relatively short tubular structure. The portion of the clamp opposite the leather strips (when in use) had the same shape as did the cross section of the oar; the inside dimension of this portion of the clamp was the same as the outside dimension of the oar; and this portion of the clamp had screws securing it to the shaft of the oar. As the clamp approaches the leather strips, it retains the same shape; but its dimension expands so that it just covers, and thereby further secures, the leather strips. According to the patent, the spacing is such that the oar lock can never contact the metallic clamp, only the leather strips. The clamp adds metallic support to the leather in acting as an oar stop; and the leather reduces friction (as compared to a metal-to-metal contact) consequently, decreasing wear and noise.
But, again, leather is not perfectly silent, absorbs water, and may not float. Furthermore, the leather strips are not readily replaceable.
The invention in U.S. Pat. No. 2,140,884 of Oscar J. Shape is a rubber sleeve for the shaft of an oar. The sleeve has a flange at one end to serve as an oar stop, is split longitudinally on one side to permit it to be placed on the shaft of the oar, and is nailed to the shaft. To have the necessary structural rigidity to serve as an oar stop, the rubber would have to be fairly hard and, thus, less than ideally silent when it contacts the metal of the oar lock--especially when rowing causes it to slide over the surface of the oar lock. In fact, the patent does not even discuss noise. The hard rubber is, additionally, unlikely to float and can be replaced only with significant effort and, of course, only by employing an entire new oar stop.
Similarly, the oar in U.S. Pat. No. 3,677,216 of Arthur J. Gentemann has a sleeve which fits around the shaft of an oar and which expands at one end to form a spherical oar stop. This would preferably be made of plastic and be cemented to the shaft. It would, therefore, have the same disadvantage as the immediately preceding patent, i.e., U.S. Pat. No. 2,140,884.
A protective sleeve around the shaft of an oar with a tabular projection from the sleeve serving as an oar stop is disclosed, but not claimed, in U.S. Pat. No. 2,252,252 of Louis H. Cross. There is no discussion of wear or noise, the materials used are not identified, and the method for attaching the sleeve to the shaft of the oar is not identified. Still, from the drawings it is apparent that the sleeve and oar stop could only be removed and replaced as a single unit.
Finally, an oar having a pentagonally shaped cross section where it fits into the oar lock is the subject of U.S. Pat. No. 231,016 of Michael F. Davis. Such portion of the shaft of the oar is conformally surrounded by a sleeve and flange that serves as an oar stop. The sleeve and flange come in two parts that are apparently held together with screws and both screwed and tacked into the shaft of the oar. There seems to be no discussion of noise, wear, or materials. The sleeve and oar stop would, however, not be readily replaceable.